Advocacy group says destruction solely meant to punish civilians living among rebel fighters and had no military justification.

BEIRUT - Syrian authorities have flattened seven residential districts for no apparent military objective but to punish civilians living among rebels who had already fled, Human Rights Watch said on Thursday.

The New York-based advocacy group published before-and-after satellite images of the destruction, along with witness testimony, in a report released on its website.

It says Syria deliberately and unlawfully demolished thousands of residential buildings in the year from July 2012, estimating the total built-up area destroyed at 145 hectares (360 acres), the equivalent of 200 soccer fields, and said many of the buildings were apartment blocks up to eight stories high.

It names the districts as Masha'a al-Arbaeen and Wadi al-Jouz in the central city of Hama, and Qaboun, al-Tadamon, Barzeh, Harran al-Awamid and Mezze airport in and around the capital, Damascus.

Reuters could not immediately reach Syrian authorities for comment on the allegations. Human Rights Watch cites Syrian officials and pro-government media as saying the demolitions were conducted to remove buildings constructed without the necessary permits or as part of urban planning efforts.

But it said "the context and circumstances" of the destruction showed it was actually intended to punish civilians living in areas that had previously housed rebel fighters.

It said the demolitions often occurred after government forces had cleared an area of rebels and in some cases extended several kilometers away from military or strategic locations which the authorities might be justified in protecting.

It said the destruction violated internationally recognized laws of war forbidding combatants from targeting civilians, and said Syrian authorities should be held accountable.

"No one should be fooled by the government's claim that it is undertaking urban planning in the middle of a bloody conflict," said Ole Solvang, a Human Rights Watch researcher.

"This was collective punishment of communities suspected of supporting the rebellion."